Method and apparatus for eliminating scale in fluid containers



April 13 ,-1926. 1,581,024

K. SCHNETZER METHOD AND APPARATUS FOR ELIMINATING SCALE IN FLUID CONTAINERS Original iled'oct. 12, 1923 INVENTOR @2296 CW ATTORN 5 30 sqale aussxe-scnnncxmisrnm, .cancnosrovnkia',-assrenon mo -1A1T'1I8OALE Lmrmn, orjYoax, ENGLAN "iron ammma scam in m communes.

coaunmaafoi A tila-lean send "m;- sea ,1 1", and ember '12,, 1923. This-application niea'my 25,1924.

- sem no. 728,278.

, amen Be it knownlt at'I, KARL 'ScHNE'rzEmf a citizen'of Czechoslovakian Republic, residing at; Aussig-Schreckenstein II, Czechoslovakia, have invented new and useful Imrovements in Methods and Apparatus for liminatin Scale in Fluid Containers, of which the ollowing is 'a specification.

.My invention relates to'processes and ap-' l parat-us for the elimination and. prevention 'of the formation in fluid containers such as, boilers, evaporators, economizers condens ers, cold water pipes, hotwate'r apparatus and the like, of'scale produced by sediment or precipitates in the fluid therein contained;

. When afluidis being processed in a cona -tainer, for example, when steam is being produced from water in a boiler, sediment; contained 111, or preci itates formed in the 9 fluid, produce a scale ike formation adher .ing to the inner surfacesof the fluid confta1ner. This'scale clogs fluid passages, re-

duces the rate at which heat may be passed through the walls of the container either to- 2 5 or from the fluid, and particularly in the case of boilers, causes over heating. and eventually burning out of the boiler shell.

In connection with steam boilers it .has-

been roposed to prevent the formation of y'the employment of electricity in such a way as to cause an electrolysis of "water for example, by conducting current nto the li uidand-causing it to flow ,into the boiler s ell. Forthis purpose electrodes are employed that are'either immersed in the liquid'in-the interior of the boiler, or "the like, as inlthe Cumberland and Siemens process orare suspended. in the feed-water tank or embedded in the earth as in the v -Renger-Fuhrmann process. It has also been proposed to' connect the apparatus to be protected, with a circuit of a source of direct current having a"moderate voltage in such a manner that the apparatus lies within the i 5 negative part of the total drop. in voltage.

- Furthermore in the British Patent No. 174,-

. 905 there is describeda process designed for theprotection of boilers and the like .in 'la which the boiler is connected to the negative 'pole of an insulated source oft-direct current at voltages between 110 and 500 volts while the positive pole remains free.

An object of my invention is .to provide a' processand apparatus for the protection of metallic fluid containers that will eliminate the formation and adhesion of scale and the like therein without injuryto the Y container itself. In the practice of my in} vention 'an electric current is used of which posed it the gases resulting from decomposition were allowed to accumulate and produce the r normal pressures ,in opposition to further decomposition. For exam- 1c, 'inthe case-of the steam boiler the liquid is water and in order to electrolytically de-. compose 'water between platinum electrodes, under such conditions that the gases of decomposition accumulate and exert atmospheric pressure, 1,7 volts are necessary to continue the electrolytic decomposition.

Thus in the elimination ofsthe formationv and adhesion of scale in steam-boilers, in. the practice of my invention, a voltage considerably less than 1.7 volts is employed because the .employment of a voltage that will,

effect electrolytic decomposition of'the water under ordinary circumstances will effect an electrolytic corrosion of the ,boiler shell. While it is my belief that in the practice of m voltage of less than 1.7 voltsproduces such electrolytic action as will prevent formation and adhesion of scale because the pressure invention, for example,-in connection with steam boilers, the employment of a of the electrolytically freed gas (hydrogen); is dissipated by the combination thereof with iron oxide to reduce the oxide, I do not intend to be bound by this theory but consider that my'invention includes the use of formation and adherence of scale is pre vented without the occurrence of electrolytic corrosionof the container or conduit. Thus currents having such a voltage that the while' 1.7 volts are required j'to' decompose water, for example, between platinum elecinvention, that will sipated, so that they trodes; because of the building up of the pressure of the free gases, a lesser voltage will effect some decomposition of water if the gases (hydrogen) are immediately disdo not build up a pressure as by being taken into combination, for example, by acting to reduce an oxide that is present, but asabove stated I do not intend to be bound by this theory.

As an illustration of the practice of my aid in the understanding thereof but to which, it is to be understood, my invention is not limited, I have found that the formation and adherence of scale in such water containing devices as steam boilers, condensers, evaporators, economizers, conduits, etc., may be eliminated by the use of electric currents at voltages from .005 to .05 volts. In accordance with my invention the voltage employed is of such value that the elimination of the formation of encrustation or scalev is efiecte'd withoutappreciably accelerating oraugmenting the corrosion of the container beyond what would normally occur in the absence of the application of current thereto for the prevention of such encrustation or scaling. The valueof the voltage that will meet both of these conditions under all circumstances cannot be specified because the voltages applied f in accordance with my invention will'vary with the circumstances surrounding the particular article to be protected. A convenient source of currents of such strength and voltage is a thermo-couple or a battery of thermo-couples, the junction of which may be heated by heat from the container or a con Venient furnace.

In the practice of my invention, the electric current employed is'conducted directly to the container and flows from the container instead of being conductedto the fluid and caused to flow from the container, or vice versa, in such a manner that the current flows across the line between. the fluid and the container. Thus in the example described, for the purpose of assisting in the understanding of my invention, a thermocouple, .or other source of a comparable electric current, will have its terminals connected to remotely spaced parts of the boiler shell preferably at points as far distant from one another as possible.

In the drawings there is shown a boiler installation embodying my invention and whereby my invention may be practiced.

1 The usual masonry setting 1 supports the boiler shell 2 which may be of any type, but

a return-tube boiler is indicated. The steam dome 3 has leading from it the main steam header 4:. The clamp 5 holds the junction point of a thermo-couple in close contact with the steam pipe and insulated wires 6 and 7-lead from the terminals of the thermocouples to opposite ends of the boiler. Thus cause appreciable electrolytic corrosion of the contalner beyond what would normally occur if such a current were not applied to and passed through the container or con duit, but which voltage is suflicient to effect elimination of the formation and adhesion of scale within the boiler.

This application is a continuation of my copending application Ser. No. 668,191, filed October 12th, 1923.

While I have described my invention in great detail and have referred to the details of a particular embodiment and application thereof, I do not intend that my invention shall be limited to such details but that it shall include such modifications and variations as fall within the hereunto appended claims.

What I claim and desire to secure by Letters Patent is:

'1. The method of protecting metallic surfaces in contact with a body of fluid against formation and adhesion of scale thereon which comprises including the metallic surace in a metallic electric circuit, causing electric current to flow in said circuit so formed while maintaining across that part of said metallic surface that is included in said circuit a voltage below that which will cause appreciable electrolytic corrosion of the metallic surface beyond what would normally occur in the absence of said voltage, and thereby preventing the formation and adhesion of scale on said surface.

2. The method of protecting metallic surfaces in contact with a body fluid against formation and adhesion of scale thereon which comprises passing an electric current through the metallic surface without di- 3. In combination with a metallic con- 1 tamer or conduit adapted for the processing of fluid, an electric thermo couple havin its terminals respectively connected to sai container or conduit at remotely spaced points thereof and being of such character and so adjusted as to protect said container or conduit against formation or adhesion of scale while producing between said oints of connection a voltage below that w ich will cause appreciable electrolytic corrosion of said container or conduit beyond what would occur in the absence of said current.

4. In combination with a metallic conage and amperage of such value as to pretainer or conduit adapted for the processing vent fo'rmatlon of scale on said container or of fluid, a source of electric current having conduit without appreciably accelerating 10 its terminals respectively connected to said velectrolytic corrosion thereof. 5 container or conduit at remotel spaced In testimony whereof, I have signed my points thereof and capable of pro ucing inname to this specification. I the circuit so formed a current having a voltv KARL SOHNETZER. 

